1. Field of the Invention
This invention relates to the field of medical diagnostic testing in general, and in particular, to an apparatus for safely transporting and chilling perishable test samples until analysis of the test samples or until the test samples can be placed in permanent storage.
2. Description of Prior Art
Medical diagnostic tests require that a variety of body fluids and tissues be removed from a patient, often in small quantity, for detailed chemical analysis. Most of these fluids and tissues are perishable, that is, if they are not preserved in a chilled environment they will "spoil" being then unsuitable for the desired analysis. The most common test sample is a blood gas sample. A blood gas sample is arterial blood, from which oxygen (O.sub.2), carbon dioxide (CO.sub.2) and other gases must be measured.
Where test samples are taken in a laboratory setting, for immediate analysis, no special measures need be taken. However, most test samples, including most blood gas samples, are taken in a setting remote from a laboratory. Such settings may be in a hospital room, in an emergency or accident ward, in a doctor's office, in an ambulance, in a home or even or a battle field. In such instances, the first four among those listed being perhaps the most common, there is an inevitable delay between taking the sample and analyzing the sample. It is simply impractical to have an orderly or special messenger take each test sample in hand and rush it to the laboratory. Firstly, as a matter of efficiency and staff limitations, samples are usually transported together, in groups. Secondly, even where such samples are rushed to a laboratory for analysis, the time of travel is usually such that special measures need be taken to preserve the samples. This is so even when traveling only between floors of the same hospital building.
When samples are to be transported by automobile, truck, airplane and the like, electrically operated refrigerators are usually available. However, for transporting samples within hospitals, and for many of those instances where refrigerators are not available in automobiles and the like, there has been only one means available for preserving and chilling test samples during transport. This one available means has been, and continues to be ice. Further, in order to insure a proper chilling effect, crushed ice or an ice bath is necessary. It is extremely inconvenient to rely on ice, as it must be produced and stored, as it is inherently messy to use and as it is often unweidly to handle. Moreover, in many instances, ice is simply not available, even for inconvenient use.
It is known that when certain chemicals are mixed together, the mixture takes place in an endothermic reaction. An endothermic reaction is driven by heat absorbed from the ambient environment. Such mixtures become cool, and in fact, some become quite cold. An example of such a mixture is water (H.sub.2 O) and magnesium sulfate (MgSO.sub.4), the latter often referred to as Epsom salts. Such mixtures, which form latent refrigerants, have been utilized by hospitals to form artificial "ice" packs. The "ice pack" comprises a plastic bag which has in it a supply of, for example, magnesium sulfate crystals and a supply of water contained in a reservoir within the bag by a rupturable membrane. The membrane is usually broken by slapping the bag on a table top or chair, whereupon the bag may be applied to the body, for example over a bruise. Although such artificial ice packs have been known for some time, they have never been used for any other purpose.
This invention overcomes the difficulties and inconvenience and transporting and preserving test samples by providing an apparatus especially constructed to hold such test samples and surround them with a supply of such a latent refrigerant after activation thereof. In the presently preferred embodiment, the apparatus is adapted to transport and preserve blood gas samples in the syringes by which they are taken, as the syringe is in fact the container in which the blood gas samples are almost always transported. This invention provides, for the very first time, a means for transporting and preserving test samples, such as blood gas, without the need for electrically driven refrigerators and without the need for ice.
An apparatus according to this invention not only provides a chilled environment for test samples, but the fluid in the reservoirs surrounding the test sample provides a cushion and protects against damage. Further, each test sample is individually transported and preserved, so that chances for cross-contamination are reduced. In one embodiment, receiving pockets are formed integrally with the leaf members and membranes. In another embodiment, the leaf members bear a clip member. In either case, the free edges of the leaf members can be held together by strips of adhesive or interlocking teeth. Accordingly, the test sample can be securely in place in a manner which prevents it from accidentally falling out of the apparatus. The outer surfaces of the leaf members can also be provided with gripping strips or portions by which a number of such apparatus can be connected on to another for simultaneous transport.